/Engine/Plugins/Experimental/LandscapePatch/Source/LandscapePatch/Public/LandscapePatchManager.h
Gets the transform from a point in the heightmap (where x and y are pixel coordinates, aka coordinates of the associated vertex, and z is the height as stored in the height map, currently a 16 bit integer) to world point based on the current landscape transform.
virtual FTransform GetHeightmapCoordsToWorld()